The present invention relates to data processing systems and more particularly to a processing system which executes completely different machine programs.
In general, systems have been provided for enabling a single processor to execute two completely different types of machine programs under microprogram control. However, where the processor of a system was required to execute programs written for different models of a family of target systems, such processor without incurring considerable costs and inefficiency could not be readily modified to execute such programs for those models of the family having different characteristics. In general, in order to provide for such a capability, it was necessary either to alter the contents of the system control store with a "new firmware load" or alter the system hardware in order to execute programs for a different model. This arrangement has the disadvantage of preventing programs written for more than model to be processed concurrently.
Also, in the type of system mentioned, often times it was necessary to convert to translate portions of the program instructions of the original system in order to be able to execute the program by the new or native system processor.
Accordingly, it is a primary object of the present invention to provide a processor capable of executing programs in any one of a number of ways other than those programs written to be executed by the processor when operated in its native mode.
It is a further object of the present invention to provide a microprogrammed processor capable of emulating the operation of a plurality of target data processing systems.